Abstract: Paraffin dissections of the structural and morphological changes during somatic embryogenesis were studied using callus tissue from Ananas comosus‘Shenwan’as material. Results showed the pineapple somatic embryogenesis can be divided into 5 phases，proembryo，globular embryo，pear embryo，bamboo shoot embryo and mature embryo. Proembryo is the multicellular structure formed by differentiation and division of embryogenic cells，club or spindle shaped，with the diameter of 50–200 μm，grey，uniform，no structural differentiation. Globular embryo is similar to a sphere with a diameter of 200–500 μm，differentiation starts at this phase and some vascular tissue were observed at the end stage of globular phase. Pyriform embryo is about 600–1 000 μm long，with different diameters between upperand lower ends，which resembles the shape of a pear，it has the largest diameter in the middle lower section (c. 400–800 μm)，and bipolarity is already showed in this phase. Bamboo shoot embryo has a resemblance to the bamboo shoot，with a length of c. 1 000–2 000 μm，the largest diameter is about 600–1 000 μm in the lower section. The cotyledon primordium，coleoptile primordium and plumule primordium are already visible at the later stage of bamboo shoot embryo. Mature embryo is about 2 000–4 000 μm long，the largest diameter is about 1 000–1 500 μm in the lower section. Cotyledon，coleoptile，leaf primordium and cotyledon growing point are shown in plumule，however，the differentiation of radical is slow，with a layer of coleorhizae tissues covering it. Both plumule and radical are endogenous，with collar-shaped cotyledon and the sheath like first leaf（coleoptiles），short hypocotyls，rosette-shaped leaf primordium on the top of hypocotyls are demonstrated as the characteristics of pineapple somatic embryo.

Key words: pineapple, somatic embryogenesis, morphology, structure